Browse Prior Art Database

Relative Position Error Sensor with Dual Prism for Optical Drive

IP.com Disclosure Number: IPCOM000117884D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Hirasaka, Y: AUTHOR [+2]

Abstract

Disclosed is a method for obtaining the relative error signal of a galvano mirror angle by using a differential signal created by the optical spots which are projected to the two detectors through dual prism.

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Relative Position Error Sensor with Dual Prism for Optical Drive

      Disclosed is a method for obtaining the relative error signal
of a galvano mirror angle by using a differential signal created by
the optical spots which are projected to the two detectors through
dual prism.

      The Figure shows an example of this apparatus.  The optical
beam (1) from the light source reflected by the galvano mirror (2) is
used for tracking to the data area on the optical disk (3).  Then the
beam (1) is divided into two directions by the prism (4).  One beam
(5) is bent to the objective lens (6) and is used for reading the
data signal or obtaining focus and tracking error signal.  Another
beam (13) goes through the prism (4) and goes to the dual prism (7).
By the dual prism divide, the beam can change the beams to two
directions (8,9).  Divided beams (8,9) are projected onto each
detector (10,11).  The angle of the galvano mirror is obtained by the
differential signal (12) from these detectors (10,11).  The signal
gain can be greater than that without dual prism (7).